1. Field of the Invention
The present invention relates to a plastic safety valve for containers, especially pallet containers with an internal container of plastic and an external jacket of metal for the transport and storage of liquids, the valve being constructed as an automatic aerating and venting valve and being integrated into a lid or plug for sealing the filling and/or emptying opening or the aerating and/or venting opening of a container.
2. Description of the Related Art
DE 25 01 228 A1 describes a sealing cap, intended for containers for liquid, which can be screwed onto the neck of a bung. A safety valve of the general type in question here is integrated into this cap to serve as an aerating and venting valve, which responds to positive and negative pressures in the container. A valve disk of elastic material is used in this safety valve; when the disk is first installed, it is put under a significant amount of pretension and thus assumes the form of a segment of a sphere. When this type of valve is used, there is the danger that fatigue phenomena affecting the valve disk material will cause leaks to form after prolonged periods of service.